This invention relates to a gas powered engine with glow plug ignition and more particularly to an improved arrangement for controlling the flow of gas to the engine and the heating of its glow plug.
There is a wide application for small internal combustion engines that are powered by gaseous fuel (LPG). Such engines may be utilized for a wide variety of purposes, for example, for small electrical powered generators. The use of gaseous fuel has a number of advantages but also presents certain difficulties. For example, it is one practice to supply the fuel to the engine at approximately atmospheric pressure. The fuel is then drawn into the engine through the negative pressure that exists in the induction system on the intake stroke. Although this arrangement has some advantages, it also may not always insure that an appropriate amount of fuel is inducted into the engine for its smooth running.
In order to avoid the aforenoted difficulties, there are advantages if the fuel is supplied to the engine at a slightly than greater atmospheric pressure. For example, if the fuel is supplied at relatively low gauge pressure (such as 0.04 kg/cm.sup.2) then the engine may operate more satisfactorily. However, when the engine is stopped or slowed significantly, this greater than atmospheric fuel pressure may cause excess fuel consumption.
It is, therefore, a principal object of this invention to provide an improved gaseous fuel supplying system for an internal combustion engine.
It is a further object of this invention to provide a gaseous fuel supply system for an internal combustion engine that operates at greater than atmospheric pressures and which will insure that the supply of fuel is discontinued when the engine stops or slows below a certain speed.
In order to maintain simplicity for the engines operated on gaseous fuel, it is practical to employ a glow plug for cold starting. Although glow plugs are effective in cold starting, it may be necessary with gaseous fuels to provide an additional amount of heat to the glow plug even during engine running. This will insure good combustion. However, if the glow plug is applied with the same current or heat during running as during starting, its life will seriously deteriorate.
It is, therefore, a still further object of this invention to provide an improved glow plug and control arrangement for an internal combustion engine.